Hi i recenty purchased a d5100 and was now thinking of buying a new lens to go with it. Has anyone purchased one of these TAMRON AF 70-300mm f4-5.6 Di LD Macro NIKON D80 D40 D60 D3100 D5100 D7000 (0725211307037) | eBay and if so are they any good? Iam new to dslr cameras so go easy on me.